As the new circuit will be placed in a hopper, the wires will have to pass through it. It is therefore necessary to intervene on the wagon body.
This is not the easiest thing to do without risk of breakage.
We must start by unclipping small lugs (3) close to the brake blocks (1), hooked at the top of the bogie crossbar. The brake and shroud assembly (2) then comes in a single block, revealing the pivot screw.
Here, I photographed a bogie without current pickup, for clarity. The presence of the current pickup strips complicates things a little more…
After removing the small screw of the printed circuit and unclipping it, the circuit / bogie assembly can be separated from the wagon.
The passage of the wires requires, depending on their size, to drill a hole with a diameter of about 2 mm in the bottom of the hopper, just below the nearest chassis crosspiece.
Since the pickup strips looked extremely fragile, I did not want to unsolder the wires connected to them. I preferred to extend these wires, disconnected from the lantern circuit, to the new circuit by soldering another wire to each and protecting the soldering with 1 mm heat shrink tubing. To the lantern circuit side, no special problem, but a sufficiently fine soldering iron tip is needed (tip for SMD).
Start by re-fixing the lantern circuit, position the wires correctly in their guides above the bogie. Reassemble the latter, pulling the excess wires to the hopper while leaving a little slack for rotation. Secure the new circuit into the hopper. I used Patafix for this: this remains easily removable.
Check operation by rolling the wagon on a piece of track. If all is right (no more blinking!), end by reassembling the brake equipment under the bogie. Check the position of the pickup strips, which tend to twist anyhow, for the last time.
Now, let’s conceal all that!